The largely hidden war between Iran and its foes seems to be heating up and spreading.

WASHINGTON - From a suspected Israeli airstrike in Sudan to cyber warfare in the Gulf and a drone shot down over Israel, the largely hidden war between Iran and its foes seems to be heating up and spreading.

Despite months of speculation, most experts and governments believe the risk of a direct Israeli strike on Tehran's nuclear program stirring regional conflict has eased, at least for now. But all sides, it seems, are finding other ways to fight.

For the US and European powers, the main focus remains on oil export sanctions that are inflicting ever more damage on Iran's economy.

But the Obama administration and Israel have also allocated resources towards covert operations - a campaign that now appears to have prompted an increasingly sophisticated Iranian reaction.

With Iranian hackers suspected of severely damaging Saudi oil facility computers and a suspected Hezbollah drone shot down over Israel, tactics and tools once seen as the sole purview of the United States are now clearly being used on both sides.

The mounting body count in Syria, some believe, is also in part a consequence of the proxy war being waged there.

Secret war becoming more brazen, risks increasing

Covert confrontation itself is, of course, nothing new. Foreign intelligence agencies have battled for decades to stop Iran and other states obtaining nuclear material, while Tehran has long used proxy battlegrounds, particularly in Lebanon and the Palestinian territories, to attack Israel.

But it does seem to be escalating. The penetration of Israeli airspace by an unmanned drone apparently operated by Lebanese militant group Hezbollah - a long-term Iranian ally - was, perhaps, one of the clearest examples so far. The drone was shot down by Israel's military in the vicinity of its main nuclear facility at Dimona.

Iran has long been believed to be putting resources into a drone program and may have gathered useful tips after a classified US Sentinel stealth drone came down in the country last year. While the Hezbollah drone was unarmed, an attack with multiple drones laden with explosives might prove harder to stop.

The dramatic spike in suspected Iranian cyber attacks this year also has some in the US distinctly worried. While direct denial of service attacks on US banks - widely seen as retaliation for US sanctions and attempts to freeze Iran from the international financial system - were seen relatively simplistic, attacks on US allies in the Gulf were more complex.

The most worrying, experts say, were those on Saudi oil firm Aramco and Qatari gas export facilities. Last month, US Defense Secretary Leon Panetta described the Saudi attack as the most sophisticated yet launched on a private company, effectively destroying tens of thousands of computers - although he stopped short of blaming Tehran directly.

Iranian officials have tended to deny involvement. But they say they have continued to come under cyber attack themselves with systems at Iran's own oil facilities, communications and infrastructure firms suffering problems last month.

"The problem is that these are secret forms of warfare that are rarely, if ever, discussed publicly," a veteran former CIA official and now a senior fellow at the Brookings Institute told an event last month. "And yet the implications could be colossal. What do we do, for example, if it turns out the Iranians can shut down the entire Saudi oil production."

In the absence of direct face-to-face negotiations, such actions can also be a diplomatic tool in their own right.